Can't compile .bas files

[PhilOfPerth]

Help!!!
I've loused something up. 
Suddenly I can't run any of my .bas progs (they've all run previously). I get  message Failed to compile C++ on all of them.
I think it's something to do with where the compiled file is placed, but I can't see how to change this. In the Run menu, the option to Output to Source Folder is selected.

Happy new year.
Same for me many times when I download an update and extract it to the same folder.
Apparently some of the files are not replaced by the new ones.
Without being sure.
So I wipe the old install and unzip again, problem solved.

Gaslouk.

Thanks Gaslouk. I'll give that a try - getting desperate now!
Edit:
Bingo! Removed all of the files ( saved my progs first) and re-extracted all again, and good as new! Thanks both.
Happy days!
And Happy New Year to all of youse.